The need for images having high resolution and high quality has recently been increasing in various fields. As the resolution and quality of an image is improved, however, the amount of data in the image is also likewise increased. Accordingly, if image data is transmitted using a medium such as an existing wired/wireless broadband line, or image data is stored using an existing storage medium, the costs of transmitting and storing data are also increased. In order to effectively transmit, store, and play information within an image having high resolution and high quality, image compression technology utilizing high efficiency can be used.
In order to improve image compression efficiency, inter-prediction and intra-prediction can be used. In the inter-prediction method, the pixel values within a current picture are predicted using as a reference the information found in other pictures. In the intra-prediction method, the pixel values of a current picture are predicted using the correlation between pixels within the same picture.
Meanwhile, as entropy coding method, there are a method using context-based adaptive binary arithmetic coding (CABAC) and a method using context-based adaptive variable length coding (CAVLC).
In the CABAC method, a probability model for each syntax element is selected depending on context, the probability values of the probability model being changed through internal statistics, and compression is performed using arithmetic coding. Alternatively, if CAVLC is used as an entropy coding model, coding is performed on each syntax element using a variable length coding (VLC) table.